


Embrace The Darkness

by ErrorDetected



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Angst, Demon AU, Fluff, M/M, Multi, Plot change, Time Travel, byleth is oblivious
Language: English
Status: In-Progress
Published: 2019-10-21
Updated: 2019-10-28
Packaged: 2020-12-27 19:16:09
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 2,053
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21123842
Author URL: https://archiveofourown.org/users/ErrorDetected/pseuds/ErrorDetected
Summary: Byleth, did not have a heartbeat. It was all because of the infusing of the Goddess’s Crest stone. Or was it...?Byleth, did not have a heartbeat. Not because of the infusing of the Goddess’s Crest stone. He was a child born from Darkness. The Goddess is known as The Beginning. The Demon King is known as The End.Byleth was blessed with the power of darkness, to defeat the darkness itself.





	1. Chapter 1

Darkness surrounded him once more. It was such a strange feeling. When his hand would fall over his heart, it would remain still and silent. The only sign that he was alive was the breaths he took, yet his appearance did not match the signs of living.

His dark red eyes gazed into the mirror as he looked at the paleness of his skin and the slight messy teal hair of his. Many said that Byleth was handsome and attractive. Yet the male never saw that; he only saw a corpse staring back at him in the mirror. Why did he look so dead? Why did he not look like the others?

Why did he have no heartbeat?

“A good question.”

Byleth looked up. Once more his red eyes stared upon the man sitting on the throne. The icy gaze of magenta stared into his own eyes, and the locks of long red hair touched to the floor.

He did not say anything in a reply to the man, who has been plaguing him with nightmares since a child. The man let out a hearty laugh as he smiled at the quiet mercenary.

“There you go once more. Staring at me with those captivating red eyes of your’s. Tell me, boy, what are you? I have been with you since birth, yet you never once acknowledged my presence. This is the first time where you would not struggle your sleeping body to wake.”

It was only silence that filled the empty void.

“...I am a mortal.” Byleth replied.

The strange man hummed, interested, as he looked at the emotionless male.

“Mortal, huh. A little hard to believe, considering your situation. A human who has no heartbeat but yet continues to live...” His voice trailed off. “I would’ve believed you if you had said you were a demon.” The man joked, a playful smile on his sharp features.

“Like you’re one to say that.” Byleth’s tone was stoic and monotone as always, yet the unintentional sarcastic bite towards the man was enough to make him laugh.

“Haha! You are such a funny one...Byleth. Yes, if I recall.”

He didn’t reply to that. Silent.

“Well, boy, it is time for you to awaken. We will meet soon.”

.

.

“-leth. Byleth!”

The said boy was awakened by his father, who shook him awake. Byleth stood up groggily and grumpy as he looked towards his father. Jeralt sighed, “Finally. Been trying to wake you up for awhile, kid...Huh?”

Byleth had this troubled expression on his face. It would look like nothing was wrong to anyone else. But this was his father, who had grown to know just about anything of Byleth. Besides his age of course. And birthday...Wow.

“Hey, kid you good?” His father asked concerned.

Yet he could only slowly nod before his brows furrowed a little. “I dreamt of that man again.”

Jeralt sighed and grew quiet for a little while before setting a rough calloused hand on his son’s head, ruffling his teal bedhead hair. Which made him tilt his head.

“Oh right. We should be going now. Everyone is—god they’re outside already.” Jeralt sighed and let his right hand press the palm-side to his forehead.

One of his father’s mercenary’s barged in and announced, “Sir! Three students have come in a request for aid. Apparently bandits ambushed them!” He reported.

Jeralt groaned “Alright. Byleth come on.”

**Notes for the Chapter:**

> Hey! I had this idea for awhile since the beginning of Three Houses’s launch. There were theories that Byleth was a demon...soo here that is put into a story! Sothis will come into play soon enough so don’t worry! There will be multiple changes to the canon story for the Blue Lions route :> but not that much to change the ending. I hope you enjoy this story!


	2. Chapter 2

Byleth remained to be silent as he obediently followed after his father. His head hurt and felt like he was caught in some sort of argument. He blamed it on that strange man in his head, who might’ve been the cause of his growing headache. Either way the mercenary couldn’t focus on that right now. In front of him stood the colors red, blue, and yellow. Well not the colors but three younger teens who were clad in them. 

He did not- was not mentally capable of listening to what they were saying. He would only tune in at some points and blink either once or twice in a gesture to show he was listening. The three future leaders of fodlan, however, only questioned his frequent blinking. 

His father and the mercenaries called it ‘The Byleth Method’. Jeralt always made a teasing remark towards his stoic son when a woman would try to catch his attention on their travels to their next assignment. But he would never respond, only nodding once or twice to the women who would take those nods as a message of interest. 

“Hey, kid, you hear that?” 

The said male blinked once with a small “Hm.” 

Jeralt groaned and looked back to the three, aware that those three were the most importance to Fodlan’s future. 

Blue boy, cleared his throat and seemed to had repeat himself “Forgive our intrusion. We wouldn’t dare to bother you if the situation were not dire.” 

And then the mercenary zones out once more. His expressionless face hard to pinpoint if he was actually listening or not, so they did not stop talking. 

Only his father knew. He raised his pointer finger and tapped at Byleth’s hand which made him rapidly blink. He exactly looked just like a baby opening their eyes for the first time. It was a gesture that his father, and the mercenaries knew to use on the boy to get his attention. Byleth was known to zone out quite a lot. 

“You lead them into battle, got it? Myself and the others will take care of most of the bandits.”

In response Byleth nodded and looked towards the three and motioned them to stand by his side.

However, the three who were talking looked at the teal haired male with uncertainty and doubt. How can a man like him, who can’t even pay attention to student’s pleas of safety- lead them into battle! A silent huff came from Dimitri, the boy dressed in blue. He didn’t want to follow him, not under his orders. He’d rather follow the Blade Breaker’s commands than some young man who couldn’t focus in a conversation.

Jeralt sensed the doubt radiating from the three kids and he narrowed his gaze. “I wouldn’t underestimate my son.” 

The mention of Byleth being his son seemed to catch the three off guard at the newfound information. Dimitri glances between Jeralt and his son before they all agreed.

“It’s all fine with me. ‘S long as I don’t die of course.” Yellow- known as Claude spoke with a smile and wink. 

Byleth did not care for words. He was never one to communicate well with in the first place, he spoke through the graceful swings of his sword. 

Unsheathing his sword, he addressed the younger three by color rather than names he did not bother to know of. “Yellow, fall behind us and take out the scattered enemies.” 

The addressed boy nodded with a two finger salute “You got it pretty boy!” 

He ignored the nickname.

“Blue and Red, you’re on my right and left. We take out the three bandits there-“ With his almost glowing, red eyes, he discreetly point his gaze towards the trees towards their right. The three understood what he was getting at and seemed surprised at his close attention to his surroundings, based on how he acted moments earlier. 

And with that Byleth, fell into the beautiful dance of death. His eyes were able to pierce through the darkness around them, the glow of the moonlight was unneeded for him while blood licked at the tip of his sword. Bodies that lunged at him immediately fell at skilled hands of a mercenary. No- the hands of the Ashen Demon. 

A certain blonde with beautiful blue eyes watched, caught in awe at his movements.

The unknown male to him, gracefully with his blade in hand- moved with the calling of death. Droplets of bright blood fell around him, stark red in the moonlight. The mercenary’s orbs almost seemed to be glowing in the presence of the crimson that spilt around him.

_ It was a terrifying sight. _

From behind him, Claude whistled at the sight before them, “Damn, talk about a keeper.” Before his hand flicked, another arrow piercing the stomach of a bandit. 

“Focus Claude, Dimitri. Now is not the time to be distracted.” Edelgard spoke sternly before charging towards another bandit with her axe in hand. 

Dimitri shook his head and focused his attention back on the battle. Yet his blue eyes let his gaze linger on the mercenary just a moment longer before the grip on his lance tightened. 

.

.

.

Byleth let out a quiet huff as he knocked the bandit leader down. The man was scruffy; teeth crooked and yellow while his personal hygiene obviously was not his  top priority for him.

“Good work Byleth!” He heard his father praise while he headed towards him on his horse.  


But he didn’t expect the bandit to come charging right back after. He jumped back to his feet, springing up from his fallen position on his back. With a battle cry and axe raised, the scruffy man prepared to swing his axe down at Edelgard as she lifted her dagger with a hardened expression. The girl was determined to not go down like this. 

“DAMN YOU!”

And the axe came down. Yet blood was not spilt from the original aimed target.

The contact never came to her. Byleth, pushed her out of the way, back turned as the pain of the sharpness of an axe slashed into his back. It crawled from his spine to his arms before it grew still and numb.

Then it was darkness once more.

Byleth opened his eyes, the redness of his orbs seemingly glowed in the darkness. There was no color around him, and the void only swallowed him up in silence. He was used to this. He was dead wasn’t he?   
  


“Another good question!”   
  


Not a stranger to the voice, he directed his attention to the throne that now appeared before him. Once more, there sat that man with long red hair- and the slitted magenta eyes. A smirk stretched across his face.

”I did tell you we would meet soon, didn’t I?”

Byleth could not answer as he looked down, “Am I dead?”

A small humming tune was all he got from the man. It made him frown as he questioned him once more “Am I?”   
  


The strange entity let out a scoffed laugh “For you to die, assumptions would also say I would as well.”   
  


Byleth didn’t understand. How could this man die? He was just some strange thing in his head. He wasn’t real.   
  


“I can hear you, you know.”   
  


He blinked once, then twice. The man took it as a sign to continue what he was saying.   
  


“Mortals certainly are interesting. Although...You are by far the most interesting one yet. Like I said boy, yourself perishing would most likely mean I as well. And well- as boring as it is here I don’t feel like perishing yet. Maybe later..just not now.” He had a toothy smile, canines as well, Byleth noted.

”Besides, dying like that was quite hilarious. Hail the darkness, it was amusing..” He trailed off. Then he pushed himself off of his throne, his dark robes dragged behind him with his red hair. The skin of his chest shown before stopping in front of Byleth.

”Byleth Eisner. There are many things you do not know. It is not your time to die.” His voice was strict and stern, much different than how he would speak to him before.

Byleth winced and his eye twitched in pain as the man held his arm in a strong, bone crushing grip.   
  
  


The sounds of wind whipped past his ears, as his eyes flickered down to his arm held in a grip. His pupils dilated and shook. Specks of dark flames and whips circled from the hand of the strange man, until it swirled around Byleth’s own arm and up.   
  


Pain circled around Byleth’s arm as a cry of agonizing pain escaped him.   
  


_“Take the darkness, dwell in it until the light consumes you at time. Embrace the darkness and challenge your fate. Death is bent to your will.” _  
  
  


Glowing Magenta eyes met with Red. A brief sight before Byleth fell into darkness once more.

**Notes for the Chapter:**

> WHEW OKAY- sorry for the wait! I’ve been pretty busy with stuff but here’s the second chapter! Lemme know your thoughts :3 It would be nice to also hear predictions as well! Thank you for spending time reading this ^-^


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